1. Field of the Invention
The present invention relates to a separator electrolytic cell. More particularly, it relates to a finger type electrolytic cell inexpensive in manufacture and suitable for a large capacity which facilitates installation or removal of a separator, especially a cation exchange membrane and further simplifies assemblage or disassemblage of anodes and cathodes.
2. Description of the Prior Art
As a process for production of an alkali metal hydroxide by the electrolysis of an aqueous alkali metal halide solution, above all, an aqueous alkali metal chloride solution, there has been heretofore proposed and practiced commercially electrolytic processes using a separator such as cation-exchange membranes. In these days environmental pollution coming from mercurial processes has come to the fore and accordingly these processes are rapidly being substituted for the mercurial processes. Most of the electrolytic cells used for these processes are filter press type cells in which, for instance, a separator such as ion exchange membrane and microporous membrane is positioned between a cathode compartment frame and an anode compartment frame to give a unit and several or several tens of the units are assembled. The cells of such type are limited in a size of each compartment and a separator has to be positioned to every unit, so that it is difficult to assemble so many units. Moreover, to each compartment a supply inlet for a solution to be electrolysed and a removal outlet for a liquor after electrolysis have to be provided. A great number of supply inlets and removal outlets provided in the anode and the cathode compartments not only require voluminous and complicated operation of connecting many units to each other upon assemblage, but also increase a risk of leakage of liquors produced by the electrolysis from connected portions. Furthermore a risk of leakage from connected portions between the compartment frames also increases inevitably as the number of compartment frames connected increases, which is said to be a fatal disadvantage to the filter press type cells. To prevent this disadvantage a strict mechanical tolerance in design as well as manufacture is needed, thereby inviting an increase in cost of manufacturing. In addition, as the number of compartment frames increases, a greater pressing force must be exerted to thus result in an increased risk of physical damages of the compartment frames and an increased cost.
For the foregoing reasons it is next to impossible to manufacture a filter press type cell of low cost and large capacity.
On the other hand, cation exchange membranes are normally produced in a form of thin sheet with the thickness of several hundred microns and limited dimensions because of making the most use of the performance thereof and of commercial factors in manufacture. That may be a reason why a filter press type cell is widely used as an electrolytic cell bearing a cation exchange membrane.
In order to eliminate the foregoing defects, Japanese Utility Model non-examined publication No. 51,333/1977 discloses an electrolytic cell which comprises anode and cathode compartments having continuously meandering concavo-convex anode and cathode, respectively, and a continuous film-like separator interposed between the anode and the cathode, the anode and cathode compartments are assembled in such a manner that the concave of the cathode or the anode and the convex of the anode or the cathode are interleaved with the separator intervened therebetween.
In the electrolytic cell of this type, however, to avoid physical damages of a separator, a gasket or a spacer must be employed to thereby maintain a clearance given between the cathode and the anode to prevent both electrodes from coming in contact with each other. Because of the clearance, cell voltage increases to thus interfere with the object of enlargement of scale.
In view of the above situation, there is a great need for an electrolytic cell to which a long size thin film-like cation exchange membrane or microporous membrane can be installed as it is and which enables the scale-up of the cell.
In the light of the foregoing problems and the present situation, the present inventors have made an extensive series of study on the development of an electrolytic cell of a large capacity bearing a long size of a separator such as a cation exchange membrane and have already proposed a novel separator electrolytic cell comprised of a plurality of anodes mounted at a bottom plate and a cathode box providing fingers interleaved between adjacent anodes, to the side surfaces of said fingers sheet-like separators being installed by means of separator installation devices located above or below the fingers.